WO2004113023A1

WO2004113023A1 - Chemical-solution supplying apparatus

Info

Publication number: WO2004113023A1
Application number: PCT/JP2003/007858
Authority: WO
Inventors: Masataka Fukuizumi; Naoki Hiraoka; Hotaka Yamamoto; Takeshi Nakamura; Hiroshi Osuda; Tooru Matoba
Original assignee: Fujitsu Limited
Priority date: 2003-06-20
Filing date: 2003-06-20
Publication date: 2004-12-29
Also published as: CN1713967A; JPWO2004113023A1; CN1713967B; JP4362473B2

Abstract

A chemical-solution supplying apparatus (100) for supplying slurry to an exterior device (7) includes a supply route (A) in which abrasive suspension flows at a predetermined flow rate and a return route (C) connecting the supply route and a storage tank (1). When the supply of the slurry to the exterior device is stopped, the abrasive suspension is returned from the supply route to the storage tank through the return route. This is done in order to maintain the flow of the abrasive suspension in the supply route so that abrasive is prevented from coagulating and settling.

Description

Technical field

The present invention relates to a chemical liquid supply apparatus, and in particular, to a chemical liquid supply apparatus for supplying a chemical liquid in which a plurality of components are mixed at a predetermined ratio to an electronic device manufacturing apparatus such as a semiconductor manufacturing apparatus or a flat panel display (FPD) manufacturing apparatus. It concerns the device. '' Background technology

In recent years, in an electronic device manufacturing apparatus such as a semiconductor manufacturing apparatus or an FPD manufacturing apparatus, various chemicals, for example, a mixed chemical manufactured by mixing a plurality of stock solutions are used in large quantities and frequently. For example, in the so-called CMP (Chemical Mechanical Polishing) process of the manufacturing process, various slurries are used as a polishing liquid. The slurry is prepared by mixing multiple stock solutions, but sedimentation and agglomeration progress in a short time. Therefore, it is required to stably supply a mixed chemical solution such as a slurry at a predetermined concentration.

A conventional chemical solution supply device weighs each stock solution and supplies it to a tank, mixes the stock solution in the tank to prepare a mixed chemical solution, and supplies the prepared mixed chemical solution to an electronic device manufacturing apparatus. The concentration of the mixed chemical is controlled by detecting the volume and weight of the chemical in the tank and calculating the mixing ratio. In some cases, the concentration of the mixed chemical in the tank is directly measured by a concentration detector. The chemical solution adjusted to a predetermined concentration in the tank is mixed using an inert gas such as nitrogen or a pump and uniformly mixed, and then supplied to an electronic device manufacturing apparatus.

The slurry prepared by the chemical supply device is used, for example, in a final polishing process of a wafer to improve the flatness of the surface of the silicon wafer. The wafer surface is polished by the mechanical stress and chemical action of the slurry applied between the polishing pad and the eno.

Undissolved substances such as abrasive grains contained in the slurry aggregate and settle over time. This aggregation and sedimentation is a problem in the manufacture of electronic devices. For example, when the agglomerated slurry is applied on the wafer, micro scratches are formed on the wafer surface. However, the yield of the wafer is reduced.

Also, the aggregation and sedimentation of undissolved substances in the slurry fluctuates the concentration of the mixed drug solution. If undissolved substances in the slurry settle in the pipe, the supply of the slurry to the electronic depice manufacturing equipment becomes unstable. In addition, in order to prevent the pipes from being blocked by the coagulated and settled undissolved substances, work is performed to remove the coagulated and settled undissolved substances. The removal operation causes a problem that the supply of the slurry to the electronic device manufacturing apparatus is interrupted.

It is conceivable to constantly agitate the slurry to prevent aggregation and sedimentation of the slurry. However, agitation of the slurry increases the frequency of collisions between undissolved substances, and may instead promote aggregation.

With some mixed chemicals, the time between production and use is limited to a short time. When such mixed chemicals are manufactured in a tank, there is a problem that the chemicals coagulate and settle before being supplied to the electronic depice manufacturing apparatus. Disclosure of the invention

An object of the present invention is to provide a chemical liquid supply device capable of stably supplying a mixed chemical liquid that is likely to aggregate or settle.

In a first aspect of the present invention, there is provided a chemical liquid supply device for supplying a chemical liquid stored in a storage tank to an external device. The apparatus includes a supply path through which the chemical flows at a predetermined flow rate, and a reflux path for returning the chemical from the supply path to the storage tank when the supply of the chemical to the external device is stopped. Is provided. ·

According to a second aspect of the present invention, there is provided a chemical liquid supply device that generates a mixed chemical liquid by mixing a plurality of stock solutions respectively stored in a plurality of storage tanks, and supplies the mixed chemical liquid to an external device. The apparatus further includes a plurality of supply paths through which the plurality of stock solutions flow at a predetermined flow rate, and a step of stopping the supply of the mixed chemical solution to the external device, the plurality of storage paths from the plurality of supply paths. The tank is provided with a plurality of reflux paths for respectively refluxing the plurality of stock solutions.

According to a third aspect of the present invention, there is provided a chemical solution supply device for supplying a slurry to an external device. The device contains abrasive grains used to prepare the slurry. A first supply path through which a first liquid containing the first liquid flows at a predetermined flow rate, and a second supply path through which a second liquid mixed with the first liquid flows at a predetermined flow rate for preparing the slurry. And a return path connected to the first supply path. When the supply of the slurry to the external device is stopped, the reflux path recirculates the first liquid from the first supply path to the first storage tank.

In a fourth aspect of the present invention, the first and second liquids are connected to a first tank for storing a first liquid and a second tank for storing a second liquid, respectively, and mix the first liquid and the second liquid. An apparatus is provided for supplying the mixture to an external device while preparing the mixture. The device includes a first supply path through which the first liquid flows, a second supply path through which the second liquid flows, the first supply path, and the second supply path. A mixer for mixing the first liquid and the second liquid; and a mixer provided in the first supply path for selectively shutting off the supply of the first liquid to the mixer. A first return path for connecting the upstream position of the first shutoff valve and the first tank in the first supply path; and a first return path for connecting the first return path to the first tank. When stopping the supply of the mixed liquid to the first reflux pulp provided on the way and the external device, while maintaining the flow of the first liquid in the first supply path, Closing the first shut-off pulp to return the first liquid to the first tank via the first reflux path; A control device for opening the reflux valve. BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is a schematic diagram of a chemical solution supply device according to a first embodiment of the present invention.

FIG. 2 is a graph showing the relationship between the air pressure for adjusting the constant pressure valve and the flow rate of the orifice.

FIG. 3 is a graph showing a conventional example of the flow rate of the orifice at the start of the supply of the abrasive grains.

FIG. 4 is an explanatory diagram showing the flow rate of the orifice at the start of the supply of the abrasive grains of the first embodiment.

FIG. 5 is a schematic diagram of a chemical solution supply device according to a second embodiment of the present invention.

FIG. 6 is a schematic diagram of a chemical solution supply device according to a third embodiment of the present invention. FIG. 7 is a schematic diagram of a chemical solution supply device according to a fourth embodiment of the present invention. BEST MODE FOR CARRYING OUT THE INVENTION

As shown in FIG. 1, the chemical solution supply device 100 of the first embodiment of the present invention prepares a chemical solution from the chemicals stored in the first storage tank 1 and the second storage tank 2, respectively. The prepared chemical solution is supplied to the electronic device manufacturing apparatus 7.

A first chemical (for example, a stock slurry such as an abrasive suspension) stored in a first storage tank 1 is pumped out by a first pump 3 and sent to a chemical mixing device 4 by pressure. A part of the first chemical pumped from the first pump 3 is returned to the first storage tank 1 in order to stir the first chemical in the first storage tank 1. The second chemical stored in the second storage tank 2 (for example, a dispersion medium for dilution for preparing a slurry by being mixed with the abrasive suspension) is pumped out by the second pump 5 and mixed with the chemical. It is pumped to device 4. Part of the second chemical pumped from the second pump 5 is returned to the second storage tank 2 in order to stir the second chemical in the second storage tank 2.

The chemical mixing device 4 includes a first supply path A for supplying a first chemical to the mixer 6, and a second supply path B for supplying a second chemical to the mixer 6. The first and second chemicals are appropriately mixed by a mixer 6 and supplied to an electronic device manufacturing apparatus 7. The mixer 6 is, for example, a static mixer.

The first supply path A is composed of an upstream pulp 8, a downstream pulp 9, an upstream pressure gauge 10, a downstream pressure gauge 11, a first constant pressure valve 12, a needle valve, and a first orifice (flow control). Means) It is controlled by a control device 15 that includes a first flow meter 14 and a first flow meter 14 and controls the chemical liquid mixing device 4.

When the upstream valve 8 is open, the first chemical pumped from the first pump 3 is supplied to the upstream pressure gauge 10. The upstream pressure gauge 10 measures the pressure of the first chemical supplied from the upstream valve 8 and supplies the first chemical to the first constant pressure valve 12. The measurement value of the upstream pressure gauge 10 is supplied to the controller 15.

The first constant pressure valve 12 reduces the pressure of the first chemical pumped from the first pump 3 to a predetermined pressure, and then supplies the first chemical to the downstream pressure gauge 11. The downstream pressure gauge 11 measures the pressure of the first chemical supplied from the first constant pressure valve 12 and supplies the first chemical to the first orifice 13. The measured value of the downstream pressure gauge 11 is supplied to the controller 15.

The controller 15 controls the first orifice 13 based on the measured values of the upstream and downstream pressure gauges 10 and 11 in order to maintain the pressure of the first chemical supplied to the first orifice 13 at a predetermined value. Adjust the air pressure to control the constant pressure valves 1 and 2.

The first orifice 13 adjusts the flow rate of the first chemical supplied from the downstream pressure gauge 11 and then supplies the first chemical to the first flow meter 14. The first flow meter 14 detects the flow rate of the first chemical supplied from the first orifice 13 and supplies the detected value to the control device 15.

When preparing a cerium slurry in which sedimentation and agglomeration of abrasive grains are likely to occur, that is, when the first chemical is a suspension (suspension) containing abrasive grains such as cerium oxide, the first pump 3 The discharge flow rate is set at 0 to 10 L Zmin, the discharge pressure of the first constant pressure valve 12 is set at 0.5 to 0.5 MPa, and the flow velocity at the first orifice 13 is set at 0 to 0.5 L / min. I prefer to be done.

The first flow meter 14 supplies the first chemical supplied from the first orifice 13 to the downstream valve 9. When the downstream valve 9 is open, the first chemical is supplied to the mixer 6. When the downstream valve 9 is closed, the supply of the first chemical to the mixer 6 is shut off.

The graph in FIG. 2 shows the relationship between the air pressure for adjusting the first constant pressure valve 12 (horizontal axis) and the flow rate of the first chemical flowing through the first orifice 13 (vertical axis). The relationship between the air pressure and the flow rate is changed according to the opening of the first orifice 13. For example, a straight line X indicates the relationship when the first orifice 13 is fully opened, a straight line Y indicates a relationship when the opening of the first orifice 13 is reduced to half, and a straight line Z indicates the relationship. The relationship when the flow rate of orifice 13 of 1 is further reduced is shown.

As shown in FIG. 2, when the first constant pressure valve 12 is operated to adjust the pressure of the first chemical, as the opening degree of the first orifice 13 increases, the flow rate increases with the pressure. The change is greater.

In the middle of the first supply path A, the first chemical flowing through the first supply path A is supplied to the first supply path A. A first return path c for returning to the storage tank 1 is connected. That is, the first return flow path C connects the output side (downstream position) of the first flow meter 14 and the storage tank 1. The recirculation valve 16 provided in the middle of the first recirculation path C is controlled by the controller 15 and is opened when the downstream valve 9 is closed. Therefore, when the downstream valve 9 is closed, the first chemical flowing in the first supply path A is returned to the first storage tank 1 via the first return path C.

The first supply path A is bypassed by the bypass path D. Specifically, the bypass path D bypasses the input side (upstream position) of the upstream valve 8 and the output side (downstream position) of the first recirculation valve 16. The bypass valve 17 provided in the middle of the bypass path D is opened when the downstream valve 9 is closed, or is kept in the normally open state. The opening of the bypass valve 17 is adjusted such that the flow rate at the first orifice 13 is maintained at 0-5 L / min.

The second supply route B consists of an upstream pulp 18, a downstream valve 19, an upstream pressure gauge 20, a downstream pressure gauge 21, a second constant pressure valve 22, and a second orifice (flow control means) 2 3 , And a second flow meter 24, and is controlled by a control device 15 that controls the chemical liquid mixing device 4.

When preparing the cellium slurry, the discharge pressure of the second constant pressure valve 22 is set to 0 to 0.5 MPa, and the flow rate of the second chemical flowing through the second orifice 23 is set to 0 to 0.5 LZ min. Preferably, it is set.

In the middle of the second supply path B, a second return path E similar to the first return path C is connected. In the middle of the second return path E, there is provided a second return pulp 25 that is opened when the downstream valve 19 is closed.

Hereinafter, the operation of the chemical solution supply device 100 will be described.

When supplying the mixed chemical solution to the electronic depice production device 7, the control device 15 causes the upstream pulp 8, 19 and the downstream pulp 9, 19 to open. Then, the first chemical is supplied from the first storage tank 1 to the mixer 6 via the first pump 3 and the first supply path A. The pressure and flow rate of the first chemical are controlled to predetermined values by the first constant pressure valve 12 and the first orifice 13.

Also, from the second storage tank 2 via the second pump 5 and the first supply path B The second chemical is supplied to the mixer 6. The pressure and flow rate of the second chemical are controlled to predetermined values by the second constant pressure valve 22 and the second orifice 23.

The first chemical and the second chemical are mixed in a mixer 6 and supplied to an electronic device manufacturing device 7. The mixing ratio of the mixed chemicals is controlled by the controller 15 based on the flow rates detected by the first and second flow meters 14 and 24.

On the other hand, when the supply of the mixed chemical solution to the electronic device manufacturing apparatus 7 is stopped, the downstream valves 9 and 19 are closed, and at the same time, the first and second reflux valves 16 and 25 are opened. Thus, the first chemical flowing through the first supply path A is returned to the first storage tank 1 via the first return path C. In other words, the first chemical keeps flowing through the circulation path including the first storage tank 1, the first supply path A, and the first reflux path C. Similarly, the second chemical flowing through the second supply path B is returned to the second storage tank 2 via the second return path E. In other words, the second chemical continues to flow through the circulation path including the second storage tank 2, the first supply path B, and the second reflux path E. Since the flow of the first chemical is always maintained in the first supply path A, aggregation and settling of the first chemical are prevented. In addition, in the second supply route B, aggregation and sedimentation of the second drug are prevented.

Cerium abrasive grains in a cell suspension are liable to aggregate and settle. Therefore, when only a part of the cell suspension flowing through the first supply path A is supplied to the first return path C, a shortage of flow in the first return path C causes the cell suspension in the first return path C. Agglomeration or sedimentation of the abrasive grains may occur. In the first embodiment, the cell suspension is supplied to the first return path C via the bypass path D. As a result, the flow rate of the first recirculation path C is increased, and the aggregation or sedimentation of the serium abrasive grains in the first recirculation path C is prevented.

According to the first embodiment, the following operation and effect can be obtained. '

(1) According to the chemical liquid supply device 100, the slurry is prepared by mixing the abrasive suspension and the dispersion medium while supplying them to the mixer 6 at a predetermined flow rate. Since the prepared slurry is immediately supplied to the electronic device manufacturing apparatus 7, sedimentation and coagulation of the slurry are prevented, and a slurry of stable quality can be supplied to the electronic device manufacturing apparatus. ' (2) When the slurry is not supplied to the electronic device manufacturing apparatus 7, the flow of the abrasive suspension in the first supply path A causes the slurry to flow to the electronic device manufacturing apparatus 7 due to the reflux through the first reflux path C. It is maintained at the same flow rate as the one being supplied. Therefore, sedimentation and agglomeration of the abrasive grains in the first supply path A are prevented, and when the supply of the slurry is resumed, the slurry having a stable quality can be promptly supplied to the electronic device manufacturing apparatus 7. . Further, also in the second supply route B, the second reflux route E can prevent the sedimentation and aggregation of the second chemical.

(3) When the flow rate of the first return path C is small, the abrasive suspension is supplied to the first return path C via the bypass path D. Therefore, sedimentation and aggregation of the abrasive grains in the first circulation path C can be prevented.

(4) When the slurry is not supplied to the electronic device manufacturing apparatus 7, the suspension of the abrasive grains in the first and second supply paths A and B is caused by the reflux of the first and second return paths C and E.流れ The flow of the dispersion medium is maintained at the same flow rate as the flow rate during the supply of the slurry to the electronic device manufacturing apparatus 7. Therefore, when the supply of slurry is resumed, the time from opening the downstream valve 9 and the downstream pulp 19 until the flow rate of the abrasive suspension and the dispersion medium supplied to the mixer 6 is stabilized is reduced. You. The reduction of the restart time will be described with reference to FIGS.

The graph of FIG. 3 shows a state in which the supply of the slurry to the electronic device manufacturing apparatus 7 is stopped by stopping the flow of the first and second chemicals in the first and second supply paths A and B. 9 is a comparative example showing a change in flow rate when slurry supply is restarted. FIG. 4 shows that the supply of the slurry to the electronic device manufacturing apparatus 7 was stopped and the supply of the slurry was restarted while maintaining the flow of the first and second chemicals in the first and second supply paths A and B. The fluctuation of the flow rate in the case is shown.

In the case of the comparative example shown in Fig. 3, when the time required for the supply flow rate to stabilize, for example, when the supply flow rate from the first supply path A is set to 20 Oml / min, the supply flow error restarts. The time required to converge within ± 1 O m L Zmin from

11 seconds. This time is for adjusting the flow rate by adjusting the constant pressure valve and orifice based on the values detected by the pressure gauge and flow meter after the supply is resumed.

In contrast, in the present embodiment, as shown in FIG. Be stabilized. This is because the flow in the first and second supply routes A and B is maintained.

Next, a chemical solution supply device 200 according to a second embodiment of the present invention will be described with reference to FIG. The second embodiment is different from the first embodiment in that a third pump 26 is provided between the mixer 6 and the electronic device manufacturing apparatus 7. The third pump 26 is preferably a pump that can appropriately adjust the discharge flow rate.

When the distance from the mixer 6 to the electronic device manufacturing apparatus 7 is long by the third pump 26, the slurry can be supplied at a stable pressure by the third pump 26.

Next, a chemical solution supply device 300 according to a third embodiment of the present invention will be described with reference to FIG. The third embodiment is different from the first embodiment in that first and second cleaning valves 27 and 28 are added.

The first supply path A can be cleaned by the cleaning valves 27 and 28. That is, valves 8, 9, and 16 are closed, and cleaning valves 27 and 28 are opened. In this state, pure water or an appropriate cleaning liquid is supplied to the first supply path A via the first cleaning valve 27, and drained via the second cleaning valve 28. In this manner, the first supply path A for supplying the abrasive suspension in which sedimentation and aggregation are likely to occur can be easily cleaned.

By closing the second cleaning valve 28 and opening the downstream pulp 9, the mixer 6 and the electronic device manufacturing apparatus 7 can be cleaned.

The cleaning liquid is supplied from the second cleaning pulp 28 to the first cleaning valve 27, and the cleaning liquid is supplied in a direction opposite to the flow of the abrasive suspension, thereby further improving the cleaning effect. Can be.

Hereinafter, a chemical solution supply device 400 according to a fourth embodiment of the present invention will be described with reference to FIG. In the fourth embodiment, two supply paths A 1 and A 2 are provided in parallel instead of the first supply path A of the first embodiment. Washing valves 29 to 32 are provided in the two supply paths A 1 and A 2 as in the third embodiment.

In the fourth embodiment, one of the two supply paths A 1 and A 2 can be cleaned while supplying the abrasive suspension to the electronic depice manufacturing apparatus 7 while supplying the other. . Since the two supply paths A 1 and A 2 are cleaned at predetermined time intervals, the supply operation of the abrasive suspension can be performed continuously. Further, even when the settling and agglomeration of the abrasive grains occur in the supply paths A 1 and A 2, the agglomerated abrasive grains are periodically removed, and the slurry is continuously supplied to the electronic deposition apparatus 7. Can be supplied.

The first to fourth embodiments may be modified as follows.

When the second chemical flowing in the second supply path B is a uniform fluid that does not settle and coagulate like pure water, the second reflux path E may be omitted.

When the second chemical flowing through the second supply path B is a non-uniform fluid that is likely to settle and aggregate, a bypass path may be provided in the second supply path B.

Claims

The scope of the claims

1. A chemical liquid supply device for supplying a chemical liquid stored in a storage tank to an external device, wherein the supply path through which the chemical liquid flows at a predetermined flow rate;

A chemical supply device, comprising: a reflux path for returning the chemical liquid from the supply path to the storage tank when supply of the chemical liquid to the external device is stopped.

2. A chemical liquid supply device that mixes a plurality of stock solutions respectively stored in a plurality of storage tanks to generate a mixed chemical solution, and supplies the mixed chemical solution to an external device,

A plurality of supply paths through which the plurality of stock solutions flow at a predetermined flow rate, and when the supply of the mixed chemical solution to the external device is stopped, the plurality of supply paths are supplied from the plurality of supply paths to the plurality of storage tanks. And a plurality of return paths for recirculating the undiluted solution.

3. A chemical supply device for supplying the slurry to an external device,

A first supply path through which a first liquid containing abrasive grains used to prepare the slurry flows at a predetermined flow rate;

A second supply path through which a second liquid mixed with the first liquid flows at a predetermined flow rate to prepare the slurry;

A reflux path connected to the first supply path, wherein when the supply of the slurry to the external device is stopped, the first supply path transfers the first slurry to the first storage tank; And a reflux path for refluxing the liquid.

4. The chemical liquid supply device according to claim 4, further comprising a bypass path for supplying the first liquid from the first storage tank to the return path in parallel with the first supply path. .

5. Each of the first and second supply paths includes:

Upstream pulp selectively opened to take in the relevant liquid from the relevant storage tank;

Pressure adjusting means for setting the discharge pressure of each supply path,

Flow rate adjusting means for adjusting the flow rate of each supply path,

The chemical liquid supply device according to claim 3 or 4, further comprising a downstream pulp that is selectively opened to supply the relevant liquid from each supply path to the external device.

6. The control device according to claim 5, further comprising a control device that controls the flow rates of the first liquid and the second liquid by operating the upstream valve, the pressure adjusting means, and the flow rate adjusting means. The chemical | medical solution supply apparatus of Claim.

7. a first cleaning valve for supplying a cleaning liquid to the first supply path;

7. The chemical liquid supply device according to claim 3, further comprising a second cleaning valve configured to discharge the cleaning liquid from the first supply path.

8. The first supply path is one of at least two parallel supply paths, and the first and second cleaning valves are provided in each of the at least two supply paths. 8. The chemical solution supply device according to claim 7, wherein

9. The pressure adjusting means detects a pressure in the supply path concerned and supplies a detected value to the control device, and is controlled by the control device based on the detected value of the pressure gauge. 7. The chemical liquid supply device according to claim 6, further comprising a constant pressure valve.

10. The flow rate adjusting means detects a flow rate of each path and supplies a detected value to the control device, and the control device controls the flow rate based on the detected value of the flow meter. And an orifice to be controlled.

1 1. Connected to a first tank for storing a first liquid and a second tank for storing a second liquid, while mixing the first liquid and the second liquid to prepare a mixed liquid An apparatus for supplying the mixture to an external device,

A first supply path through which the first liquid flows,

A second supply path through which the second liquid flows,

A mixer connected to the first supply path and the second supply path, for mixing the first liquid and the second liquid;

A first shutoff valve provided in the first supply path, for selectively shutting off supply of the first liquid to the mixer;

A first return path connecting the upstream position of the first shut-off valve and the first tank in the first supply path;

A first reflux valve provided in the middle of the first reflux path,

When the supply of the mixed liquid to the external device is stopped, the first liquid is supplied through the first reflux path while maintaining the flow of the first liquid in the first supply path. A control device that closes the first shut-off valve and opens the first reflux valve to return to the tank.

12. A second shutoff valve provided in the second supply path for selectively shutting off the supply of the second liquid to the mixer;

A second recirculation path connecting the upstream position of the second shut-off valve and the second tank in the second supply path;

A second reflux valve provided in the middle of the second reflux path, wherein the control device stops supplying the mixed liquid to the external device, The apparatus according to claim 11, wherein the second shut-off pulp is closed and the second reflux valve is opened for returning to the second tank via the return path.

13. When supplying the mixture to the external device, the control device opens the first and second shut-off pulp and closes the first and second reflux valves. The apparatus of claim 12, wherein

14. The first liquid according to claim 13, wherein the first liquid is a suspension containing abrasive grains, the second liquid is a diluting liquid for diluting the suspension, and the mixed liquid is a polishing slurry. apparatus.